The present invention relates to the medical field of intraluminal wires used to access distal areas of the body. Specifically, the present invention relates to wires partially coated with a lubricious material. The coated wire may be used to construct a guide wire with a central core and surrounded by the coated wire coiled around the core. Alternatively, the partially coated wire may be used to construct a variety of devices including baskets, snares, laparoscopic instruments or small coils that may be used within numerous medical specialties, including cardiology, urology, and radiology.
Minimally invasive medical procedures can be performed at remote sites by inserting and navigating endoscopic equipment into and through blood vessels or body lumens to the treatment site. A specific site may be difficult to reach for many reasons including vessel or tract tortuosity, lumen constriction e.g. edema or tumor impingement or lumen blockage e.g. ureterolithiasis.
Insertion of a guide wire can facilitate access to the treatment site. Catheters or medical tools can then be advanced over the guide wire to the specific site. To achieve accurate placement the guide wire should incorporate the somewhat competing features of pushability, kink resistance, torqueability and bendability. Guide wire designs known in the art to meet these criteria include a guide wire design characterized by a solid metal core surrounded by a metal coil. Metals for the core may include spring steels, stainless steels and NiTi alloys. The same variety of metals used as core materials can be used for the coil wire, including stainless steel or NiTi alloys such as NITINOL wire. The coil wire may be round wire or flat wire; the coil wire may be made of a single wire strand or may be made of multifilar wire. The coil wire may wrap around the entire length of the core or only a portion of the core. The adjacent turns of the coil wire may or may not be tightly wrapped with succeeding turns of the coil wire touching, the coil wire may be wrapped around the core in an open fashion, or the core may be surrounded by coil wire that is tightly wrapped along a portion of the core and open wrapped along a subsequent portion of the core. The coil can be, but need not be, in axial compression.
Important to smooth advancement and retraction of the guide wire is an exterior surface of the guide wire that creates minimal friction between the inner wall of the vasculature or body lumen and the exterior surface of the guide wire. Similarly, to advance catheters or other equipment over or along a guide wire, a balance is required between ease of movement of the catheter or equipment along the guide wire and retention of the desired positioning of the guide wire at the treatment site.
Guide wire construction typically includes use of a pre-coated coil wire to minimize friction between the external surface of the guide wire and the inner wall of the bodily lumen or medical equipment. The guide wire could, however, be spray coated after assembly to increase lubricity.
Circumferential coating of the wire coil may interfere with or prevent desired bonding (including adhesive, weld, and solder) between the coil wire and core. Abrasion between adjacent coated coils of the coil wire may result in flaking or sloughing of coating material. Abraded particles of coating material could enter the vascular or body lumen.
Construction and use requirements of various other coated medical wires and endoscopic instruments, such as urology baskets and snares, laparoscopic instruments or radiology coils may mimic the construction and use requirements of a coated guide wire.
The invention pertains to a wire partially coated with a lubricious material. The present invention provides benefits over the prior art by providing a wire that is coated only along a portion of the wire perimeter. The lubricious coating is deposited on the wire along the exterior perimeter portion of the wire that could have direct contact with either an internal body lumen or an inner lumen of a catheter. Lubricious materials for coating select portions of the wire include PTFE and hydrophilic materials such as HYDROPASS or GLIDEX. A single material may be coated along the selected portion of the wire, or different materials may be applied along different segments of the wire.
The uncoated portions of the wire provide surfaces for bonding to other materials that are preferably free of interference from the coating material. For example, guide wire construction may require bonding between a wire core and wire coil surrounding the core. The uncoated portions of the coil wire provide a surface preferably free from a coating material; such uncoated portion may more readily enhance bonding between the core and the coil wire.
If the partially coated wire is formed into a coil configuration, such as may occur in construction of a guide wire, where interstices of the coils are preferably uncoated, the potential for coating material flake-off or rub-off resulting from abrasion between adjacent turns of the coiled wire is reduced or eliminated.